Extrusion press for cable sheathing



Feb. 9, 1960 J. E. LAWTON ETAL 2,924,332

EXTRUSION PRESS FOR CABLE SHEATHING 4 Sheets-Sheet 1 Filed Sept. 18, 1953 ow & NW m Inventor; W

W zmm y W 14ttomejs Feb. Q, 1960 J. E. LAWTON ETAL 2,924,332

EXTRUSION PRESS FOR CABLE SHEATHING Filed Sept. 18, 1953 4 Sheets-Sheet 2 Inventors JWWM A ttorneya Feb. 9, 1969 J, LAWTON ETAL 2,924,332

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Feb. 9, 1960 J. E. LAWTON ETAL 2,924,332 EXTRUSION PRESS FOR CABLE SHEATHING 4 Sheets-Sheet 4 Filed Sept. 18. 1953 In ven tor 5 Joh i/wardla f v fiden'rl'flankl Bloc 4'98 2,924,332 EXTRUSION PRESS FOR CABLE SHEATHING John Edward Lawton, London, and Frederick Daniel Brookes, Hayes, England, assignors to British Insulated Callenders Cables Limited, London, England, a British company Application September 18, 1953, Serial No. 381,104

Claims priority, application Great Britain September 23, 1952 5 Claims. (Cl. 207-4) This invention relates to ram presses for the extrusion of metal. It deals particularly with presses having co-operating inner and outer dies employed for the extrusion of a tubular body, which may be a sheath of an electric cable. It is applicable to presses of the kind in which the dies are mounted with their axes transverse to the axis of the container from which metal is forced by the ram to and between the two dies and also to presses of the kind in which the dies are mounted with their axes in line with that of the container and its ram.

In the present usual construction of such presses the dies are mounted in parts of the press inwhich considerable strains are produced during the operation of the press. For example, the dies may be mounted on diecarrying members held in a die block or housing which is held against the front end face of the container so that although a separate member it is structurally associated with the container in such a manner that it is subjected to the strains experienced by the container and its adjacent parts. In a particular form of press having transversely mounted dies and comprising a press body comprising two opposed containers placed in line and having oppositely acting rams pressing on the metal in the containers and delivering the plastic metal into an extrusion chamber between the two containers, the dies and their carriers may be housed in a transverse bore in the press body, one die-carrying member being secured to one side of the press body and the other 'to the diametrically opposite side of the body. In a press of the kind in which the dies are in alignment with the container a usual ar rangement is for the female die to be held in a die block held against the front face of the container and for the male die to be carried by a member held at the rear end of the container.

In all such cases a result of this close association of the dies and their carriers with other members of the press is the production of relative displacement of the two dies so that the distance between them (which defines the thickness of the wall of metal extruded) is greater when the press is under load than when the load pressure is relaxed, as is necessary for recharging a container in the case of continuing extrusion from one charge after another. The relaxation, accordingly reduces the thickness of the wall of extruded metal which lies between the dies when it occurs. The marks caused by this are known as stop marks. They may be noticeable faults, even when lead is being extruded; they become more so when harder metal, such as aluminum, forms the wall, since the forces which are released are greater in that case.

'The direct cause of this change of dimensions is the combined action of two things. One of these is the straining of the press body by internal pressure in such a Way as to increase the distance between the points of support for the die-carrying members. The'other is the compressive straining of the die-carrying members lying between the dies and the points of support. These two effects add nited States Patent 0 The object of the present invention is to mount the dies in such a way that stop marks are negligible, even when aluminium is being extruded.

In accordance with the invention, the two dies are mounted in alignment in a housing which is a separate member associated with the press body but having attachment to the press body at only one place, this place being of limited length in the direction of the axis of the dies. One or more than one passage is provided in the wall of the housing for the lateral entry of the metal in passing from the container to the dies. By .attachment is here meant a connection such that there is in the region concerned no relative displacement between the housing and the adjacent part of the press body so that the housing shares in any movement of the adjacent part, especially any movement parallel with the axis of the dies. By reup to produce the increase in the spacing between the dies.

striction of this attachment to a single axially short region our housing, unlike the usual die box type of housing, for instance, which has attachment over a region of considerable axial length, does not have imparted to it strains corresponding to those in the container or other parts of the press body adjacent to it. Moreover, although the housing will elongate to some extent under forces exerted by the metal passing into it and between the dies, the strain is made to be of small value by keeping the length of the stressed part of the housing small. This strain may be decreased by putting the stressed part of the housing under endwise compression simultaneously with the application of pressure to the container ram, the endwise compression (that is compression in the direction of the die axis) being applied by means which have similar freedom to that of the housing from strain imposed by the adjacent parts of the press. This counter-stressing has the effect of increasing tIhe effective modulus of elasticity of the housing materia The housing may conveniently be tubular and of circular shape both internally and externally, and be formed with a port, or ports, in its circumferential wall which or each of which, permits a lateral entry of extrusion metal to a central chamber which is somewhat larger than the largest die to be housed in it. The seatings in the housing by which the dies are supported against the pressure exerted by the extrusion metal are placed as near together as is practicable. One die can be directly held in a recess in the housing which it fits, the other must be adjustable endwise to enable the correct wall thickness of the extruded metal tube to be obtained.

Attachment of the housing to the press is preferably made at one end, that is away from the ported central portion. For instance, when the housing is placed in a transverse bore in the press body, attachment may be made by setting the housing against an abutment acting on one end of the housing or one face of a collar thereon or one end of a member secured to the housing. In the second case the collar may be held on its seating as by a nut working in an internally screw threaded part of the wall of the transverse bore. Alternatively attachment may be made by mounting the housing at its delivery end in or on the inside of the end wall of the container of the press in the case where the direction of extrusion is parallel with the movement of the ram in the container.

To enable the invention to be more fully understood and readily put into practice an example of our improved die housing fitted to a double ram press will be described with the aid of the accompanying drawings, wherein- Figure 1 is a general view partly in elevation and partly in section in a plane normal to the axis of a twin container press fitted with a preferred form of our die housing,

Figure 2 is an enlarged longitudinal section through the die housing shown in Figure 1,

Figure 3 is a cross-section taken on the line III-III'in Figure 2,

3 Figure 4 is plan view partly in section on the line IV-IV of Figure 1 of the press shown therein, i

On referring to Figures land 2 of the drawings, it will be seen that thehousing l for the male and female dies 2 and 3, respectively, located in a'transverse bore ,4 of a press body comprising a massive walled cylinder-5 con sisting of inner and outerparts 5a and 5brespective1y and having a through axialfbore 6, see Figure 4. 'The ends of this cylinder f orm tw o v a xially alignedbillet coritainers having :srr s t miner-e Jw r i "i h m h hous'ing l is of tubular form and both externally and internally of circular cross-section. It is asliding fit in the central part of the "transverse bore .4, the end portions of that bore being o f larger diameter asishbwn at 7 to facilitate removalofj'thelhousing 1 The housing l has at its delivery end a central aperture 7 8 large enough tolpermit the tree passage of the largest extruded" body to Ybe produced by the V press 7 when titted with this particular housing; Behind this aperture} the housingis boredout toalarger diameter to form a recess 9 to receive the outer die 3, in which recess n is a close fit. Behindthis recess9lthe interior of the l nusing is enlarged by' the provision of a substantially rectangular lateral passage 10 of whicl1.'tl1e'cent'ral.part form an extrusion gham ber 11 within fwh ich lies the innerdie 2v and of which the ends form ports leading from this extrusion chamber to the twocontainens vforthei inetal to be extruded. Immediately to jthe rear of the extrusion chamber'the bore of the housingis reduced as shown at 12 to provide a short cylindrical bearing for "the tubular mandrel13 carrying the inner die 2 which, .in this fc ase, is integral with the mandrel. Beyond .thisbearin g there is an enlargement 14 to accommodate a'collarfi1 5 on the mandrel. The rear face ofthis collar I Sis engaged by an axially adjustable abutment formed by the frontend face of a tube nut 16 working in the screwthreadedlrear.end 1 7 of the bore of the housing 1. This nut extends beyond the rear end of the housing and the projecting part has means by which it can be engaged and rotated to adjust its axial position andthat of the die 2 reiative to theihousing land the die 3. Such means may, as shown, consist of a set of radially projecting pins 18 which canenter slots 19 in the end of a tubular spanner 20 which is an easy fit in the adjacent outer end part 1 .of the through :transverse'bored in the press body. l

Attachment of i "e housing 1 to tbe press body maybe effected bymeans'of a tubular ram 21 which is supported t its rea i ti by a or zontal crossr cam 2,2. This be l be Ba d is s surfid ny .conventional manner at its endsfto the ends oflthe rams 24 of a pair of parallel hydraulic packs 25 mounted on a vertical Support plate 26 secured to the press body by tie rods 27, two above and two below the jacks 25 and the cross beam 22, whichtie rods screw into the two cross heads 28 by which the press body 5 is sup'ported. The ram 21 engages the rear end of the mandrel 13. As the latter is held is supported on a against its seating on the nut 16 by the pressure of the metal the housing 1 is etiectively held against movement in a direction counter to the direction of extrusion.

To facilitate the adjustment of the inner die 2 by means of the tube nut 16 which surrounds the rear end of the mandrel 13 and supports the same endwise, part of which adjustment has to bemacle when the press is under load, pressure may be exerted on the rear end of the mandrel 13 by theram 21 whilst supporting the opposite end of the housing. This. relieves the threads of the nut 16 of pressure exerted by theextrusion metal, whilst the adjustment is being made: While tbis adjustment operation is taking place the housing is effectively prevented from rotating with the .nut 16 by the metal in the ports through which metal enters the housing, During this adjustment operation, the housing I is displaced slightly to bring its delivery end into engagement with a tubular member 29 entering the front or delivery end of thetransverse bore 4' and bearing 'atits outer end against a centrally apertured horizontal beam 30 located with respect to the press body 5, one end of the beam 30 being secured by bolts 31 and a strap 32 to the adjoining container cross head 28 and the other end being secured in a corresponding manner to the second container cross head. The housing will thus also a be frictionally held against rotation by being clamped between ram 21 and member 29. It will be understood that i normally, i.e. when no adjustment of the die is being made, there will be a clearance '33 between the housing 1 and member 29,.the mandrel13 being forced back against the ram 21 or its equivalent by the reaction pressure due to the extrusion in the opposite direction.

Alternatively the housing may be attached to the press body by means of the tubular spanner 20 which may be supported by the cross beam 22 through a detachable spacing collar 34 which may be removed when it isdesired to relieve the threads" of the tube nut 16 of pressure exerted by the extrusion 'metal. Yet another way of attaching'thehousing'l to the press body is to.

position the fixed support member 29 to the rear of the housing 1 andto make the outer die ormatrix 3 adjustable by means of a tube nut and a; tubular spanner within, which may work the ram 21 for relieving the tube nut of pressure exerted by the extrusion metal.

T 0 indicate approximately the dimensional relation obtained in the example of housingdescribed with references to Figures 1 to 3, the following figures are given: For use with a container cylinder of 4 /2 inches internal diameter and to extrude sheaths of aluminum up to 0.8 inchdiameter, the housing has a length of 7 inches overall and a length of directly stressed part of 3V2 inches. This part, is that extending between the seating for the outer die and thethread engaged by the rear nut. It compares with a length of about 20 inches which would result if the dies were mounted directly on the external wall of the container or a die box so closely associated with the press body as to share in the strain movement of'that body. i

What we claim as our invention is 1. A double ram metal extrusion press comprising a press body having a through axial bore whose ends form a pair of axially aligned billet containers and having a through transverse bore intersecting said axial bore, a ram working in each billet container, a one-piece tubular housing slidable in said transverse bore, inner and outer extrusion dies located within said tubular housing, ports the circumferential wall of said tubular housingleading, one from one of said containers and in said housing, and means for aifording saidhousing uni-lateral support in an axial direotion,'said means comprising a single tubular member slidable in said transverse bore for engaging one end of said tubular housing and means external to said transverse bore for positioning said slidable tubularmember in said-transverse bore;

2. A metal extrusion press comprising a press body including a containerfor extrusion metal, a tubularhousing havinga stepped bore and being .a sliding fit in a transversebore in said press body and having at least one port .for the entry of metal .from said container, means affording said'housing uni lateralsupport in an axial direction" in said transverse bore, an outer extrusion die within said stepped bore and seatingagainst a step in said bore, .amandrel having on its front end an inner die to the rear: of .saidzouterdie, said mandrel being slidablein said stepped bore, a tubular nut screwing into the rear end of .saidihousing and forming an abutment for saidmandrel and projecting rearwardly of said housing, and means" for engaging said rearwardly projecting portionofrsaid tubular nut and rotating said nut in said housing whereby to adjust the axial position. of said inner die. relativetosaid outerdie. 1

3; A metal extrusion press comprising: a press body including a container for .extrusionmetal, a tubular housinshaving: assteppedboreand being a slidingfit'in a transverse bore in said press body and having at least one port for the entry of metal from said container, means affording said housing uni-lateral support in an axial direction in said transverse bore, an outer extrusion die within said stepped bore and seating against a step in said bore, a mandrel having on its front end an inner die to the rear of said outer die, said mandrel being slidable in said stepped bore, a tubular nut screwing into the rear end of said housing and forming an abutment for said mandrel and projecting rearwardly of said housing, means for temporarily supporting the front end of said housing and hydraulic means for applying pressure temporarily to the rear end of said mandrel to relieve the threads of said nut of pressure exerted by the extrusion metal, and means for engaging and rotating said rearwardly projecting portion of said tubular nut, whilst its threads are relieved of said pressure, to adjust the axial position of said inner die relative to said outer die.

4. A metal extrusion press comprising a press body including at least one container for extrusion metal communicating with a bore in said press body extending transversely to the container axis, a tubular housing for 6, extrusion dies placed in said transverse bore, inner and outer extrusion dies in alignment with one another in and supported by said housing against the thrust exerted by the extrusion metal at least one port in the wall of said housing for the entry of metal into said housing from said container, an abutment within said transverse bore for supporting one end of said tubular housing, and means for positioning said abutment in said transverse bore and securing it to said press body, said tubular housing being otherwise free to slide axially relative to said press body.

5. A metal extrusion press as claimed in claim 4 wherein said means comprises a press-body-attached beam supporting the abutment and the inner die.

References Cited in the file of this patent UNITED STATES PATENTS 515,951 Cobb Mar. 6, 1894 1,109,555 Summey Sept. 1, 1914 1,167,626 Claremont et al Jan. 11, 1916 2,782,920 Norman Feb. 26, 1957 

